Good & Bad Fibre

Good fibre, Bad fibre - How The Different Types Affect You

Fibre can influence many aspects of health. From gut bacteria to weight loss, it is often considered a fundamental part of a healthy diet. Most people have a very basic understanding of fibre, and tend to lump it all into one category.

However, the truth is that not all fibre is created equal. Some types are highly beneficial, while others can cause digestive problems in some people.This blog explains everything you need to know about the different types of fibre.

What is fibre and How is it Classified?

“Fibre” refers to a diverse group of carbohydrates that humans cannot digest. We lack the digestive enzymes required to break them down, so they pass through most of the digestive system unchanged.

The recommended intake is 38 grams for men, and 25 grams for women. However, most people are only eating around half of that, or 15-17 grams per day. Fibre is mostly found in plant foods, including vegetables, fruits, legumes, whole grains, nuts and seeds.

There is actually a huge variety of different fibres found in foods. The problem is that they are often classified in different ways, which can be highly confusing.

Fibre is formally classified into two main types:

· Dietary fibre: Fibre found naturally in foods.

· Functional fibre: Fibre that is extracted and isolated from whole foods, then added to processed foods.

However, there is a major problem with classifying fibre in this way. It tells us absolutely nothing about their health effects. A popular alternative method is to classify fibre based on its

· Solubility (soluble vs insoluble)

· Viscosity (viscous vs non-viscous)

· Fermentability (fermentable vs non-fermentable)

Then there is yet another class of nutrients called resistant starches, which are often classified as dietary fibres.

BOTTOM LINE:

Fibres are indigestible carbohydrates found naturally in plant foods. They are often classified as either dietary (found naturally) or functional (added to foods).

Soluble vs Insoluble Fibre

The solubility of fibre refers to its ability to dissolve in water. Based on this, fibre has often been categorized as either soluble or insoluble:

Soluble fibre blends with water in the gut, forming a gel-like substance. It can reduce blood sugar spikes, and has various metabolic health benefits.

Insoluble fibre does not blend with the water and passes through the digestive system mostly intact. It functions mostly as a “bulking” agent, and may help speed the passage of food and waste through your gut.

Soluble fibres include gums, pectin, psyllium, beta-glucans and others. Insoluble fibres include lignin and cellulose. Different plant foods have varying proportions of soluble and insoluble fibres.

BOTTOM LINE:

Fibre is often categorized based on its ability to dissolve in water. Soluble fibre has various benefits for metabolic health, while insoluble fibre functions mostly as a bulking agent.

Fermentable Fibre

An estimated 100 trillion live bacteria reside in the human gut, mainly in the large intestine. These bacteria are actually crucial for optimal health in humans. They play various roles related to weight management, blood sugar control, immunity, brain function and mental health. They are so important that they are often referred to as the “forgotten organ”. Because humans can’t digest fibre, it ends up reaching the large intestine mostly unchanged.

This is where fermentable fibre comes into play. These are fibres that the friendly gut bacteria are able to digest (ferment) and use as fuel. This increases the number and balance of friendly gut bacteria, which also produce short-chain fatty acids with powerful health benefits.

Most fermentable fibres are soluble, but there are also some insoluble fibres that can function in this way. Fermentable fibres include pectin, beta-glucans, guar gum, inulin and oligofructose.

The best whole-food sources of fermentable fibres are beans and legumes. A one cup serving often provides up to half of the recommended daily intake of fibre. All that being said, one of the by-products of fibre fermentation is gas. This is why foods high in fermentable fibre can cause flatulence and stomach discomfort, especially if people are not used to eating a lot of fibre.

BOTTOM LINE:

Fermentable fibre is digested and used as fuel by the friendly bacteria in the gut. This can lead to various beneficial effects on health.

Viscous Fibre

Some types of soluble fibres form a thick gel when they blend with water. These are known as viscous fibres. Put simply, the viscosity of a fluid refers to its “thickness.” For example, the sweetener honey is more viscous than water.

When you eat viscous fibre, it forms a gel-like substance that “sits” in the gut.

This slows down the digestion and absorption of nutrients, resulting in a prolonged feeling of fullness and reduced appetite.

A review of 44 studies on fibre treatments found that only viscous fibres reduced food intake and caused weight loss. Viscous fibres include glucomannan, beta-glucans, pectin, guar gum and psyllium. Good whole-food sources include legumes, asparagus, Brussels sprouts, oats and flax seeds.

BOTTOM LINE:

Viscous fibres form a gel-like substance that sits in the gut, leading to enhanced feelings of fullness, reduced appetite and weight loss.

Resistant Starch

Starches are the main types of carbohydrates in the diet. They are long chains of glucose molecules, found in potatoes, grains and many other foods. Some starch is actually resistant to digestion, so that it passes through the digestive system unchanged.

This type of starch is called resistant starch, and it functions like soluble, fermentable fibre in the gut.

Resistant starch has numerous powerful health benefits. It improves digestive health, enhances insulin sensitivity, lowers blood sugar levels and significantly reduces appetite.

There are several good food sources of resistant starch, including green bananas, various legumes, cashews and raw oats. A more detailed list can be found here. Additionally, certain starchy foods tend to form large amounts of resistant starch if they are cooled down after cooking. This includes white potatoes and white rice. Raw potato starch is also very high in resistant starch, and some people eat it as a supplement

BOTTOM LINE:

Resistant starch is a type of starch that escapes digestion. It functions like soluble, fermentable fibre, and has numerous health benefits.

Unique Fibres That Are Worth Highlighting

Several fibres have specific health implications, and are worthy of highlighting.

Fructans

A fructan is the term used to describe a small chain of fructose molecules.

Oligofructose and inulin are the two main fructan varieties in the diet. They can feed the friendly bacteria in the gut, and have been shown to help treat certain types of diarrhea.

However, fructans are also classified as FODMAPs, types of carbohydrates known to cause digestive issues in many people. In fact, fructans and other FODMAPs trigger adverse symptoms in 3 out of 4 people with irritable bowel syndrome, a common digestive disorder. The biggest source of fructans in the modern diet is wheat.

Beta-Glucan

The health benefits of beta-glucans have been extensively documented. These fibres have a specific molecular structure that makes them highly viscous in the gut. Beta-glucans can improve insulin sensitivity and lower blood sugar levels. They can also significantly reduce cholesterol levels and increase feelings of fullness. The main food sources of beta-glucans are oats and barley.

Glucomannan

Glucomannan is a viscous fibre that is commonly marketed as a weight loss supplement. Numerous studies have shown that glucomannan can cause modest weight loss, fight constipation and improve risk factors for heart disease.

BOTTOM LINE:

Fructans are fibres that can cause adverse digestive symptoms in some people. Beta-glucans and glucomannan are soluble, viscous fibres with potent health benefits.

Take Home Message

Fibres that are soluble, viscous and fermentable seem to be the healthiest, by far. Resistant starches are also incredibly healthy.

Good sources of healthy fibres include vegetables, fruits, oats, legumes, nuts, dark chocolate, avocados, chia seeds and various other foods.

However, there is probably no need to obsess over the details here. As long as you are eating plenty of whole plant foods, then your fibre intake should take care of itself.

Hope you will find the above information are useful. I would appreciated if you can kindly add your comment or feedback below. Thank you.